General Question

What happens if a fly/mosquito/whatever harmful insect flies through your mouth and into your stomach?

I used to read a fictional story about a person who had a mosquito fly into their stomach, and yup, it took a big surgery to finally rescue them. The doctor said that the mosquito could “cause death since it bites the internal organs and leaves serious infection/diseases” and could “live and drain blood from the inside”.

Well, that was just one made-up story. I wonder what would happen in real life, if something similar happened. Would the insect cause death, or would they be dead themselves inside our body?

Yes, they would be dissolved in the digestive tract, no worries.
I recently found out though that my particular blood type is Malaria resistant, good to know if I run away to a tropical place without any vaccines. haha

The only “bugs” you have to worry about swallowing are the ones specifically designed to survive the rigors of the digestive tract, and they are few and far between. More to the point, of those which can cause you trouble, very few of them can fly.

Stomach acid kills everything, as it is supposed to. It is our natural defense against bacteria in food. That is why it is not a good idea to go crazy with the antacids as that neutralizes that defense.